Move audio decoding to protocol layer

remoting/protocol/connection_to_host.h

Index: remoting/protocol/connection_to_host.h
diff --git a/remoting/protocol/connection_to_host.h b/remoting/protocol/connection_to_host.h
index 4a8d537b2580fbdd5f0a9a6ce4c23981c0eab4a6..2f894ad5a33ba3fe49511edc7a36e3ff014f201e 100644
--- a/remoting/protocol/connection_to_host.h
+++ b/remoting/protocol/connection_to_host.h
@@ -9,8 +9,13 @@
 #include <string>
 
 #include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
 #include "remoting/protocol/errors.h"
 
+namespace base {
+class SingleThreadTaskRunner;
+}  // namespace base
+
 namespace remoting {
 namespace protocol {
 
@@ -71,8 +76,13 @@ class ConnectionToHost {
   virtual void set_client_stub(ClientStub* client_stub) = 0;
   virtual void set_clipboard_stub(ClipboardStub* clipboard_stub) = 0;
   virtual void set_video_renderer(VideoRenderer* video_renderer) = 0;
-  // If no audio stub is specified then audio will not be requested.
-  virtual void set_audio_stub(AudioStub* audio_stub) = 0;
+
+  // Initializes audio stream. Must be called before Connect().
+  // |audio_decode_task_runner| will be used for audio decoding. |audio_stub|
+  // will be called on the main thread.
+  virtual void InitializeAudio(
+      scoped_refptr<base::SingleThreadTaskRunner> audio_decode_task_runner,
+      base::WeakPtr<AudioStub> audio_stub) = 0;
 
   // Initiates a connection using |session|. |event_callback| will be notified
   // of changes in the state of the connection and must outlive the